1. Field of the Invention
The present invention relates to the art of railway track assemblies and more particularly, to an embedded railway track structure using elastomeric elements.
2. Description of the Related Art
Construction of railroad tracks along streets has long presented the problem of how to provide long-lasting serviceability and track evenness with the road surface, while still giving needed access to the rails and supporting structures at lesser expense than has previously been possible.
Where tracks are embedded in pavement it is necessary to have a gutter to contain each rail, yet is must also be possible to gain access to the rail, its supporting structures, and fasteners attaching the rail to the supporting structures, once the gutter has been sealed.
Many highways and arterials which cross railroad tracks utilize elastomeric crossing elements. Crossings, using elastomeric elements not only are inherently smoother than crossings made from non-elastomeric materials, but maintain their smoothness much longer.
Timber crossings, for example, wear quite quickly and soon present a rough crossing surface. While asphalt wears better than timber, it is difficult to compact asphalt immediately adjacent to the rails. Thus, an asphalt grade crossing soon settles adjacent to the rails which also creates a rough surface. In addition, it is difficult to prevent water from entering between the asphalt and the rails and when freezing occurs the water expands and causes deterioration of the asphalt. Concrete wears better than asphalt and does not require mechanical compaction, however, freezing is a problem with this material also. In addition, concrete grade crossings usually have metal edges which occasionally causes shorting to occur between the rails which can activate the crossing signs.
Not only do elastomeric grade crossing elements provide greater smoothness, they are easier to remove than timber, concrete or asphalt which permits them to be reused when the track is brought up to grade by adding ballast and retamping.
Raymond U.S. Pat. No. 4,793,545 discloses sealing insert assemblies which extend along the length of the rails of an embedded track, but which appear likely to be costly to construct and yet unable to provide access to the rail support structure for repair.
Davis U.S. Pat. No. 5,181,657 discloses a grade crossing system including elastomeric pad units located along each side of the rails for supporting automobile traffic crossing railroad tracks. The disclosed structure, however, requires specially pre-cast panels which rest on the pads, making such structure undesirably expensive for use along a railway track embedded in a paved street.
Lucas U.S. Pat. No. 5,609,294 discloses a railroad track assembly that includes rubber filler bodies held in place along the sides of each rail by retainer strips which lock into place on the filler bodies. A retainer form is placed over the top of the rail and filler bodies, holding the filler bodies in place closely alongside the rail. Paving material is placed alongside the rail structure, including the retainer form, whose depending legs act as a form for the paving material to define a slot alongside the filler bodies. The disclosed structure, however, requires the retainer form to be removed from atop the rail and filler bodies and the retainer strips are forced into the slot making the structure undesirably expensive and its installation time consuming.
Additionally, in order to avoid undesired unevenness of the surface of a street across or along which a railroad track runs, it is desirable that the pavement surface be approximately level with the height of the top of the rails of the track and that appropriate resilient filler structure be provided between the pavement and each rail to support motor vehicle traffic. Such filler structures are an added expense and, moreover, must not interfere with passage of railroad cars along the track.
What is desired, then, is a structure for railroad tracks embedded in a roadway, which is easier and less costly than previously used structures yet can provide long-lasting serviceability and track evenness, while still giving needed access to the rails and supporting structures at lesser expense than has previously been possible.
The present invention overcomes the aforementioned shortcomings of the prior art and provides a railway track structure that is serviceable and maintains its evenness after extended use. The railway track structure includes a pair of spaced parallel rails, secured by fasteners to transversely extending crossties or support beams. Each rail has a base portion, a head portion and a web portion integrally connecting the head and base portions. A plurality of rail clips, formed from an elastomeric material, include a cavity for receiving the rail fastener and engage the rails at spaced apart positions. An elastomeric boot formed as a continuous piece encases the rail. The boot includes a body having two exposed top surfaces, an inner surface, and an outer surface. The boot extends from the base portion of the rail to cover substantially all of an outer surface of the head portion. The rail clips contact an outer surface of the boot near the base portion of the rail. A pair of preformed filler bodies, formed from an elastomeric material, reside alongside a respective outer surface of the rail boot body and are in sealable contact with the rail boot body. The bottom surface of the filler bodies are engagingly attached to a respective rail clip.
In this manner, the railway track structure of the invention may be assembled to provide a grade crossing or a so-called grass track roadway which both enjoy a substantially coplanar surface with the top surfaces of the rails.